Over a black basecoat, I laid out my initial cracks. I used VMC Ivory here, which I've found does a good job of covering black without have to put it down 15 times. As you can see, the initial pass just get everything roughly in place. I then went back and thinned down the cracks a bit to get them sharper and and more to the scale I was going after. The Ivory also provides a nice base to work the red/orange/yellow off of. Trying to get it bright over black would be tough.
Next I added RMC Big Top Red. It's a nice, dark red, but unfortunately I think might have only been available during ReaperCon this year. I followed this up by covering nearly everything with RMC Magma Red which is a nice bright orangy-red. I finished this by once again thinning and sharpening the lines.
Now we start to really get that hot lava look that I am shooting for. I took some RMS Lava Orange (good choice, eh?) and picked out some of the hotter areas. I then took some Reaper Pro Paint Sunlight Yellow and picked out some smaller areas and finally VMC white for the brightest hotspots.
I think this comes off nicely, but I would be interested to see the same effect with some of those fluorescent pigments/paints out there.
I've got more cracking to do and will be extending it further down the legs, up towards the head and onto the tail as well, but I wanted to get this out for you all to see.